Q: What is the best way to care for a lilac bush? The leaves have brown spots now. — Stacey Ferguson, email
A: Lilacs can be affected by several leaf spot diseases but they don't seem to be fatal if the plant is kept healthy. Although they're not as common here as they are in the North and Midwest, lilacs can thrive in North Georgia. The key seems to be planting a variety that can handle warm winters. I've had good success with 'White Angel' and 'Dark Knight'. I have more comments and a list of good varieties at bit.ly/GAlilac.
Q: On my new property I want to get the soil as healthy as I can before planting anything. Is it beneficial to apply mycorrhizal fungi? I want to restore the native microbiome. — Jeffrey Brown, Barnesville,
A: Mycorrhizae are helpful soil fungi that bring water and nutrients to plant roots. The research about mycorrhizae is decidedly mixed as to its ability to improve growing conditions in different situations. Soil scientists say that mycorrhizae might help with certain infertile soils but would be useless in most others. I think you'd get the best native biome by shredding local leaves and using them for mulch or as a tilled-in soil amendment. Ask your new neighbors about local farms that have animal manure you could till in as well.
Q: My neighbor's tree holds water in a limb crotch. Should she drill a hole so the water can drain? — Judy B.
A: Tree experts agree that drilling a drainage hole is a bad idea. The tree is able to "wall off" the wet area all by itself, with no human help. Drilling a drain hole just gives rot fungi a good route into the trunk. My advice is to leave it alone but keep an eye out for mosquitoes that might breed in the water. You can use a "mosquito doughnut" to keep them away.
Q: Our neighbor's large oak tree fell over and uprooted during a violent rainstorm while they were out of town. How common is it for an apparently healthy large tree to fall over? — Sue Baum, Lawrenceville
A: It’s a truism that well-anchored trees rarely fall over. Trees, as they grow, sense when and where to produce anchor roots. These structural roots bind to the soil, anchoring the tree so it can grow tall and withstand wind and water loads. But anchor roots can be severely damaged by careless installation of driveways, sidewalks or plumbing lines. The tree can appear healthy if its feeder roots are active, but once the anchor roots are gone the tree is living on borrowed time since anchor roots rarely regenerate. If any kind of trenching is done inside a tree’s drip line, a certified arborist should be hired to evaluate plans and to suggest techniques that minimize damage to anchor roots.
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